In preparation for microscopic investigations, the samples to be investigated, which can e.g. involve a histological section, are usually placed onto a specimen slide and treated with a coverslipping medium, which preferably has a refractive index adapted to the refractive index of the coverslip or of the specimen slide and functions as an adhesive, before a coverslip is then applied. Because coverslipping of the sample is usually a very time-consuming procedure, coverslipping machines are often used for this.
An apparatus for handling specimen slides and coverslips is known, for example, from DE 101 44 048 A1. With this apparatus, a coverslip is respectively received with the aid of a receiving unit guided via an actuation arm, and set onto a desired position on the specimen slide.
A variety of defects can occur in the process of coverslipping. For example, it may happen that the coverslip completely or partly fractures, which can result in the emergence of coverslipping medium as a further defect. As a further defect, air inclusions beneath the coverslip can occur; these can have a disadvantageous influence on a later microscopic investigation, or make it in fact impossible.
When defects occur in the coverslipping process, they are often noticed only upon microscopic examination. This leads to a number of serious problems for routine laboratory operation, since at this point it time it is often not possible to re-coverslip the sample. Especially when a plurality of samples are to be investigated, for example in a continuous throughput, such defects result in a considerable diminution in the overall investigation efficiency of the laboratory, since the entire process sequence, and not just the coverslipping process, becomes disrupted.
U.S. Pat. No. 5,566,249 discloses an apparatus for detecting air bubbles in the coverslipping medium. The apparatus comprises image-generating means with which an image of the coverslip can be generated, and which can be embodied as an automated scanning microscope. Means for recognizing bubble edges, and for further image processing, are also provided.